The present invention relates to paper machines.
In particular, the present invention relates to the headbox of a paper machine, and especially to that type of headbox which is provided wth an air tank for containing air under pressure to equalize pressure fluctuations in the pulp suspension flow.
Thus with a construction of this type the volume of air which is under pressure in the air tank communicates with the pulp suspension flow, the pulp suspension discharging from the headbox through a slice thereof. The pulp suspension is received by a distribution header which delivers the pulp suspension to turbulence passages from which the pulp suspension flows to the slice.
Thus it is already known to use in connection with the headbox of a paper machine or at the approach pipe system of the headbox air tanks which communicate with the pulp suspension flow so that it is possible to attenuate pressure fluctuations and disturbances in the pulp suspension flow. However, up to the present time such air tanks have been situated well to the rear of the slice of the headbox so that the pulp suspension can flow through a considerable distance beyond the air tank before reaching the slice and thus can develop undesirable pressure fluctuations between the air tank and the slice. Although it is obviously desirable to situate the air tank as close as possible to the slice, it has always been necessary to situate the air tank at a location which is undesirably spaced from the slice because the construction of the headbox at the region of the slice thereof is such that an air tank cannot be accommodated directly at the region of the slice through which the pulp suspension discharges from the headbox.